/*
 * Copyright (C) 2012 Google Inc.
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */

package interactivespaces.activity;

/**
 * The control commands for an activity.
 *
 * @author Keith M. Hughes
 */
public interface ActivityControl {
	/**
	 * Start up the activity.
	 * 
	 * <p>
	 * This method should alter the activity state.
	 * 
	 * <ul>
	 * <li>If the startup was successful, the activity state should be
	 * {@code ActivityStatus.RUNNING}.</li>
	 * <li>If the startup was unsuccessful, the activity state should be
	 * {@code ActivityStatus.STARTUP_FAILURE}.</li>
	 * </ul>
	 */
	void startup();

	/**
	 * Shut the activity down.
	 * 
	 * <p>
	 * This method should alter the activity state.
	 * 
	 * <ul>
	 * <li>If the shutdown was successful, the activity state should be
	 * {@code ActivityStatus.READY}.</li>
	 * <li>If the shutdown was unsuccessful, the activity state should be
	 * {@code ActivityStatus.SHUTDOWN_FAILURE}.</li>
	 * </ul>
	 * 
	 * <p>
	 * This method can be called several times in a row. Any time after the
	 * first call should do nothing.
	 */
	void shutdown();

	/**
	 * Activate the activity.
	 * 
	 * <p>
	 * This method should alter the activity state.
	 * 
	 * <ul>
	 * <li>If the activation was successful, the activity state should be
	 * {@code ActivityStatus.ACTIVE}.</li>
	 * <li>If the activation was unsuccessful, the activity state should be
	 * {@code ActivityStatus.ACTIVATE_FAILURE}.</li>
	 * </ul>
	 */
	void activate();

	/**
	 * Activate the activity.
	 * 
	 * <p>
	 * This method should alter the activity state.
	 * 
	 * <ul>
	 * <li>If the deactivation was successful, the activity state should be
	 * {@code ActivityStatus.RUNNING}.</li>
	 * <li>If the deactivation was unsuccessful, the activity state should be
	 * {@code ActivityStatus.DEACTIVATE_FAILURE}.</li>
	 * </ul>
	 */
	void deactivate();
}
